Preeclampsia is a leading cause of maternal death and increases perinatal death five-fold. There is compelling evidence that maternal endothelial dysfunction contributes to the pathogenesis of preeclampsia. Hypertriglyceridemia, decreases in high density lipoprotein (HDL) cholesterol, and abnormally small-sized low density lipoprotein (LDL) particles are characteristic features of preeclampsia. We have proposed that these lipid abnormalities promote endothelial dysfunction in preeclampsia through the generation of oxidative stress. Lipoprotein lipase (LPL) plays a vital role in the clearance of triglycerides from the circulation. The importance of LPL defects in the development of cardiovascular disease is increasingly recognized. Several common variations in the LPL gene promote the triad of increased triglyceride, decreased HDL cholesterol, and small-sized LDL. The dyslipidemic effects of these functional variants are accentuated by pregnancy. In our Caucasian population, a sum total of 18.8% of preeclamptics are heterozygous for either the N291S or D9N coding sequence variants of the LPL gene, compared with 4.6% of normal pregnancy controls. Accordingly, Aim 1 is to test whether these observations can be generalized to other populations. We will compare the prevalence of the four most common, functional variants in the LPL gene in Caucasians and African-Americans from western Pennsylvania, and in Icelandic women. Aim 2 is to sequence the coding and promoter regions of the LPL gene to identify other functional variants, which will then be genotyped in cases and controls. We posit that variations in the LPL gene the predispose to dyslipidemia are over-represented in women with preeclampsia. Aim 3 is to compare plasma lipids, lipid peroxidation products, and markers of endothelial dysfunction in women with preeclampsia stratified by genotype. We hypothesize that, among women with preeclampsia, those carrying LPL variants with reduced enzymatic activity will display an especially adverse blood profile. In Aim 4, we will measure plasma LPL enzyme activity in women 12 weeks postpartum to further test the hypothesis that a constitutional deficiency in LPL (hormonally and/or genetically mediated) is associated with preeclampsia. In Aim 5, we will explore the effects of heterozygous LPL deficiency on endothelial regulation of vascular function during pregnancy, using the LPL knockout mouse. This systematic approach will help to clarify the link between dyslipidemia and the pathogenesis of preeclampsia and could provide clues to prevention or treatment of the disorder.